Gap-detecting mechanism in the seed germination ofMallotus japonicus (Thunb.) Muell. Arg., a common pioneer tree of secondary succession in temperate Japan |
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Authors: | Izumi Washitani Akio Takenaka |
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Institution: | (1) Institute of Biological Sciences, University of Tsukuba, 305 Tsukuba, Ibaraki, Japan;(2) Institute for Environmental Studies, 305 Tsukuba, Ibaraki, Japan |
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Abstract: | Germination responses ofMallotus japonicus (Thumb). Muell. Arg. seeds to temperature revealed a gap-detecting mechanism in the seed germination of the species. Among
various constant and alternating temperatures examined in the range from 12–40°C, only very limited temperature regimes were
found to be favourable for seed germination, specifically, alternating temperatures between 18–32°C and 28–40°C. A single
several-hour higher-temperature (32–40°C) treatment could also induce the germination of seeds which had been imbibed for
several days at a constant temperature in the range of 20–26°C, suggesting that there is a process requiring higher temperature
among the overal germination processes. Seeds located at or near the surface of denuded soil would have a good chance of experiencing
such a temperature change when several rainy days are followed by fine weather, while seeds beneath close vegetation would
not. On the other hand, the pressence or absence of light or a simulated ‘canopy ligh’ had little effect on the germination.
Therefore, it was concluded that the seeds ofM. japonicus have a ‘gapdetecting mechanism’ in the form of a higher-temperature requirement of a certain process involved in the overall
germination processes. |
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Keywords: | Gap-detection Mallotus japonicus See germination Temperature |
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